This invention relates to a device and method for generating and accelerating a plasma to detonate an explosive such as an insensitive explosive or energetic material. The improved detonator is employed to replace conventional mechanical "flying plate" devices used in detonating such materials.
A review of the prior art literature reveals that large railgun accelerators have been employed for propelling one gram projectiles to velocities of 20 kg per second, for launching payloads into orbit, and even to obtaining projectile velocities of 100 kg per second or more. Such a discussion is, for example, provided in the paper prepared by R. S. Hawk entitled "Railgun Accelerators for Launching 0.1 gram Payloads at Velocities Greater Than 100 km per Second," dated June 15, 1979 and presented at the DOE sponsored Impact Fusion Workshop, July 10-13, 1979 at the Los Alamos Scientific Laboratory, and which disclosure is incorporated by reference herein. In this paper, a railgun accelerator is discussed as being a linear DC motor consisting of a pair of rigid, field-producing conductors and a moveable conducting armature. The armature is accelerated as a result of the Lorentz force F produced by the magnetic field B of the rail currents interacting with the current I in the armature throughout its width w wherein, ##EQU1## and L.sub.1 is the specific railgun inductance in H/m, and m is the mass of the projectile. Typically, the armature is a thin plasma arc that impinges on the backside of a dielectric projectile and accelerates it. The arc is presumed to be confined behind the projectile by the conducting rails on the two sides and dielectric rail spacers inbetween.
To supply the current to the prior art railguns, a primary energy storage device (PESD), such as a capacitor bank or a homopolar generator (HPG), and a pulse-forming or storage inductor L.sub.0 is employed. Accordingly, such a device has been proposed to launch impactors of 1 to 10 grams of mass or more at velocities of 20 km per second or more at low cost. (See also, for example, "Railgun Accelerators for Gram-sized Projectile" IEEE Transactions in Nuclear Science, NS-28, No. 2, April 1981 by R. S. Hawk, which disclosure is also incorporated by reference.)
In a related aspect, U.S. Pat. No, 3,916,761 to Fletcher et al., discloses a device for accelerating a projectile to extremely high velocities which includes a light gas accelerator to impart an initial high velocity to the projectile on a plasma accelerator and compressor receiving the moving projectile, and then accelerating it to higher velocities. As in the case with the Hawk's device, projectile velocities on the order of 20 km per second can be obtained for use in the accelerator in the field of meteoroid simulation.